Electrode assembly and lithium battery comprising same

ABSTRACT

Provided is a stacked electrode assembly including: a lowermost electrode arranged on a lowermost portion of the stacked electrode assembly; an uppermost electrode arranged on an uppermost portion of the stacked electrode assembly; at least one unit stacked body arranged between the lowermost electrode and the uppermost electrode and including a positive electrode, a negative electrode, and a separator, the separator being arranged between the positive electrode and the negative electrode; and a separator arranged between the lowermost electrode and the at least one unit stacked body, and between the at least one unit stacked body and the uppermost electrode. A capacity and energy density of a lithium battery may be improved by employing an electrode including a mesh electrode current collector as the lowermost electrode or the uppermost electrode of the stacked electrode assembly.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This is the U.S. national phase application based on PCT Application No.PCT/KR2018/002239, filed Feb. 23, 2018, which is based on Korean PatentApplication No. 10-2017-0030270, filed Mar. 9, 2017, the entire contentsof all of which are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an electrode assembly and a lithiumbattery including the same.

BACKGROUND ART

Unlike the primary battery which is generally not rechargeable, asecondary battery is referred to as a rechargeable battery and has beenwidely used in the field of compact high-tee electronic apparatusesincluding digital cameras, mobile apparatuses, and notebook computers. Amedium and large-scale battery is also under development, andparticularly, with distribution of an electric vehicle (EV), ahigh-capacity safe secondary battery is under development.

Examples of a secondary battery include a nickel-cadmium battery, anickel-metal hydride battery, a nickel-hydride battery, and a lithiumsecondary battery. Among these batteries, a lithium secondary batterymay be used for a high-power EV by connecting several batteries inseries. Since a lithium secondary battery has a high operation voltageand an excellent energy density characteristic per unit weight comparedto a nickel-cadmium battery or a nickel-metal hydride battery, use of alithium secondary battery gradually increases.

Therefore, there is a demand for a lithium secondary batteryrepresenting a high capacity and having a high energy density.

DESCRIPTION OF EMBODIMENTS Technical Problem

Provided is a stacked electrode assembly in which an electrode includinga mesh electrode current collector is arranged on an uppermost portionand/or a lowermost portion of the electrode assembly.

Provided is a lithium battery having a high capacity and a high energydensity by employing the stacked electrode assembly.

Solution to Problem

According to an aspect of the present disclosure,

a stacked electrode assembly includes:

a lowermost electrode arranged on a lowermost portion of the stackedelectrode assembly;

an uppermost electrode arranged on an uppermost portion of the stackedelectrode assembly;

at least one unit stacked body arranged between the lowermost electrodeand the uppermost electrode and including a positive electrode, anegative electrode, and a separator, the separator being arrangedbetween the positive electrode and the negative electrode; and

a separator arranged between the lowermost electrode and the at leastone unit stacked body, and between the at least one unit stacked bodyand the uppermost electrode,

wherein the lowermost electrode or the uppermost electrode includes anelectrode including a mesh electrode current collector.

According to another aspect of the present disclosure, a lithium batteryincludes the stacked electrode assembly.

Advantageous Effects of Disclosure

The lithium battery according to an embodiment may have an increasedcapacity and an improved energy density by including a stacked electrodeassembly in which an electrode including a mesh electrode currentcollector is arranged on an uppermost portion and/or a lowermost portionof the stacked electrode assembly.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 to 4 are cross-sectional views of electrode assemblies accordingto different embodiments.

FIG. 5 is a view showing a thickness reduction effect of a negativeelectrode including a mesh electrode current collector compared to anegative electrode including a non-porous electrode current collector.

FIGS. 6 to 8 are cross-sectional views of the structures of electrodeassemblies according to different embodiments.

FIGS. 9 to 11 are cross-sectional views of a negative electrodeincluding a mesh electrode current collector that is applicable to anelectrode assembly according to an embodiment.

FIG. 12 is a view for explaining forming of a negative electrodeincluding a mesh electrode current collector.

FIGS. 13A to 13D are photos of various shapes of mesh electrode currentcollectors.

FIG. 14 is a photo of a mesh electrode current collector having adifferent number of openings or different aperture ratios.

FIG. 15 is a view of an electrode current collector having a metalfoam-shaped three-dimensional opening according to a comparativeexample.

BEST MODE

According to an aspect of the present disclosure,

a stacked electrode assembly includes:

a lowermost electrode arranged on a lowermost portion of the stackedelectrode assembly;

an uppermost electrode arranged on an uppermost portion of the stackedelectrode assembly;

at least one unit stacked body arranged between the lowermost electrodeand the uppermost electrode and including a positive electrode, anegative electrode, and a separator, the separator being arrangedbetween the positive electrode and the negative electrode; and

a separator arranged between the lowermost electrode and the at leastone unit stacked body, and between the at least one unit stacked bodyand the uppermost electrode,

wherein the lowermost electrode or the uppermost electrode includes anelectrode including a mesh electrode current collector. Both thelowermost electrode and the uppermost electrode may include an electrodeincluding the mesh electrode current collector.

The electrode including the mesh electrode current collector may furtherinclude an electrode active material located on one side of the meshelectrode current collector.

The electrode including the mesh electrode current collector may furtherinclude an electrode active material located on two opposite sides ofthe mesh electrode current collector.

The electrode including the mesh electrode current collector may have anasymmetric shape in which a thickness of an electrode active materiallocated on one side thereof is different from a thickness of anelectrode active material located on another side thereof.

The electrode including the mesh electrode current collector may furtherinclude an electrode active material located inside an opening of themesh electrode current collector.

An electrode not including the mesh electrode current collector mayinclude a non-porous electrode current collector and an electrode activematerial arranged on at least one side of the non-porous electrodecurrent collector.

The at least one unit stacked body may have a bi-cell structure stackedin a sequence of a negative electrode, a separator, a positiveelectrode, a separator, and a negative electrode (or a sequence of apositive electrode, a separator, a negative electrode, a separator, anda positive electrode).

The mesh electrode current collector may have a metal mesh shape inwhich a plurality of openings are arranged in a two-dimension.

The mesh electrode current collector may include at least one of Al, Ti,V, Cr, Mn, Fe, Co. Ni, Cu, Zn, Zr, Nb, Ag, W, Pt, steel use stainless(SUS), and a combination thereof.

A thickness of the mesh electrode current collector may be 10 μm to 500μm.

The electrode including the mesh electrode current collector may includean electrode active material located on one side of the mesh electrodecurrent collector, and the number of openings (ppi) of the meshelectrode current collector may be 30 or more per inch or an apertureratio of the mesh electrode current collector may be 40% or less.

The electrode including the mesh electrode current collector may includean electrode active material located on two opposite sides of the meshelectrode current collector, and the number of openings (ppi) of themesh electrode current collector may be 30 or less per inch or anaperture ratio of the mesh electrode current collector may be 40% ormore.

According to another aspect of the present disclosure, a lithium batteryincludes the stacked electrode assembly.

Mode of Disclosure

As the disclosure allows for various changes and numerous embodiments,example embodiments will be illustrated in the drawings and described indetail in the written description. However, this is not intended tolimit the present disclosure to a particular embodiment and it should beunderstood that all changes, equivalents, and substitutes included inthe spirit and the scope of the present disclosure are included in thepresent disclosure. In the description of the present disclosure,certain detailed explanations of the related art are omitted when it isdeemed that they may unnecessarily obscure the essence of the presentdisclosure. It will be understood that although the terms “first”,“second”, etc. may be used herein to describe various components, thesecomponents should not be limited by these terms. These terms are onlyused to distinguish one component from another. The terms used in thepresent specification are merely used to describe exemplary embodiments,and are not intended to limit the present disclosure. An expression usedin the singular encompasses the expression of the plural, unless it hasa clearly different meaning in the context. In the presentspecification, it is to be understood that the terms such as“including,” “having,” and “comprising” are intended to indicate theexistence of the features, numbers, steps, actions, components, parts,or combinations thereof disclosed in the specification, and are notintended to preclude the possibility that one or more other features,numbers, steps, actions, components, parts, or combinations thereof mayexist or may be added. As used therein, “/” may be interpreted as “and”,or interpreted as “or” depending on a case.

In the drawings, a thickness is enlarged so as to clearly express aplurality of layers and regions. Throughout the specification, likereference numerals are used for similar elements. It will be understoodthat when a layer, region, or component is referred to as being “formedon,” another layer, region, or component, it can be directly orindirectly formed on the other layer, region, or component.

Hereinafter, the disclosure will be described more fully with referenceto the accompanying drawings, in which example embodiments of thedisclosure are shown. When description is made with reference to thedrawings, like reference numerals in the drawings denote like orcorresponding elements, and repeated description thereof will beomitted. In the drawings, a thickness is enlarged so as to clearlyexpress a plurality of layers and regions. Sizes of some of layers andregions in the drawings may be exaggerated for convenience ofexplanation.

Generally, a lithium battery is completed by inserting an electrodeassembly to a case having a square shape, a cylindrical shape, a pouchshape, etc., and then injecting an electrolyte. The electrode assemblymay be classified into a jelly-roll type (winding type) and a stackedtype depending on a structure thereof, the jelly-roll type winding longsheet positive electrode and negative electrode with a separatortherebetween, and the stacked type sequentially stacking a plurality ofpositive and negative electrodes having a predetermined size with aseparator therebetween.

In the stacked electrode assembly, an electrode located on an outermostportion, that is, an uppermost portion or a lowermost portion includes anon-reaction area in which intercalation/deintercalation of lithium iondoes not occur and thus an irreversible capacity may increase. Since anincrease of an irreversible capacity deteriorates a life characteristicof a lithium battery, minimization of an irreversible capacity isrequired.

As a result of reviewing a method that may minimize an irreversiblecapacity, it is revealed that a battery may be implemented, the batteryreducing an irreversible capacity and increasing an energy density bymaking an uppermost and/or lowermost electrode of the stacked electrodeassembly different from electrodes located inside the stacked electrodeassembly.

Hereinafter, the present disclosure is described in detail.

A stacked electrode assembly according to an aspect of the presentdisclosure includes:

a lowermost electrode arranged on a lowermost portion of the electrodeassembly; an uppermost electrode arranged on an uppermost portion of theelectrode assembly; at least one unit stacked body arranged between thelowermost electrode and the uppermost electrode, and including apositive electrode, a negative electrode, and a separator, the separatorbeing arranged between the positive electrode and the negativeelectrode; and a separator arranged between the lowermost electrode andthe at least one unit stacked body, and between the at least one unitstacked body and the uppermost electrode,

wherein the lowermost electrode or the uppermost electrode includes anelectrode including a mesh electrode current collector.

Here, the electrode may be a positive electrode or a negative electrode,and electrodes sequentially stacked around the separator may havedifferent polarities. In other words, the electrode assembly may have astructure stacked in a sequence of a positive electrode, a separator,and a negative electrode (or a sequence of a negative electrode, aseparator, and a positive electrode).

For example, both the lowermost electrode and the uppermost electrodemay be electrodes including the mesh electrode current collector.

The electrode including the mesh electrode current collector in theelectrode assembly may further include an electrode active materiallocated inside an opening of the mesh electrode current collector.

Here, the mesh electrode current collector is discriminated from a plaincurrent collector such as a foil-shaped thin plate. The mesh electrodecurrent collector denotes a current collector including a plurality ofopenings arranged two-dimensionally inside a sheet-type base material.The electrode including the mesh electrode current collector may have astructure in which an electrode active material is located inside anopening of the mesh electrode current collector.

Other electrodes except the electrode including the mesh electrodecurrent collector in the electrode assembly may include a non-porouselectrode current collector, for example, a non-porous electrode currentcollector such as a metal thin plate, and an electrode active materialarranged on at least one side of the non-porous electrode currentcollector. That is, in the electrode not including the mesh electrodecurrent collector, an electrode active material and a current collectorare sequentially stacked, and the electrode not including the meshelectrode current collector has a boundary by which the electrode activematerial and the current collector are clearly distinguished in thestacking sequence. Therefore, a structure of the electrode not includingthe mesh electrode current collector is different from a structure ofthe electrode including the mesh electrode current collector in which anegative electrode active material or a positive electrode activematerial is located inside an opening of the mesh electrode currentcollector.

In the case of a stacked electrode assembly including only an electrodenot including the mesh electrode current collector, an irreversiblecapacity increases due to a lowermost electrode or an uppermostelectrode as described above. Therefore, to solve this issue, it may beconsidered to use an electrode in which an active material is notarranged on a lowermost portion or an uppermost portion thereof, thatis, to use an electrode in which an active material is arranged on onlyone side of a current collector. However, an electrode in which anactive material is arranged on only one side of the current collectormay have a bending phenomenon in which a polar plate is bent during arolling process.

In contrast, in a battery that employs an electrode including a meshelectrode current collector as a lowermost electrode or an uppermostelectrode, the polar plate bending phenomenon may not occur and capacityreduction by an uppermost electrode or a lowermost electrode may notoccur. Therefore, compared to a battery that employs the stackedelectrode assembly including only an electrode not including the meshelectrode current collector, a capacity and an energy density of thebattery that employs an electrode including a mesh electrode currentcollector may be increased.

The unit stacked body may have a full-cell structure stacked in asequence of a positive electrode, a separator, and a negative electrode(or a negative electrode, a separator, and a positive electrode).

In another embodiment, the unit stacked body may have a bi-cellstructure stacked in a sequence of a negative electrode, a separator, apositive electrode, a separator, and a negative electrode (or a positiveelectrode, a separator, a negative electrode, a separator, and apositive electrode).

Hereinafter, embodiments are described in more detail with reference tothe drawings.

FIGS. 1 to 4 are cross-sectional views of a stacked electrode assembly100 according to an embodiment. Referring to FIGS. 1 to 3 , theelectrode assembly 100 includes a lowermost electrode, an uppermostelectrode, and one unit stacked body u1 arranged between the lowermostelectrode and the uppermost electrode. Referring to FIG. 4 , theelectrode assembly 100 includes a lowermost electrode, an uppermostelectrode, and two unit stacked bodies u1 and u2 arranged between thelowermost electrode and the uppermost electrode.

As shown in FIG. 1 , the lowermost electrode of the electrode assembly100 may be a negative electrode 50 including a mesh electrode currentcollector 51. The electrode assembly 100 may have a structure in whichthe negative electrode 50, a separator 10, the unit stacked body u1, theseparator 10, and a negative electrode 30 are sequentially stacked, thenegative electrode 50 including the mesh electrode current collector 51,and the unit stacked body u1 including a positive electrode 20, theseparator 10, the negative electrode 30, the separator 10, and thepositive electrode 20 that are sequentially stacked.

Also, though not shown in the present specification, the electrodeassembly 100 may also have a structure in which the positive electrode40, the separator 10, the unit stacked body u1, the separator 10, andthe positive electrode 20 are sequentially stacked, the positiveelectrode 40 including the mesh electrode current collector, and theunit stacked body u1 including the negative electrode 30, the separator10, the positive electrode 20, the separator 10, and the negativeelectrode 30 that are sequentially stacked.

In this case, in the electrode assembly 100, electrodes may be stackedsuch that the electrodes having different polarities face each otherwith the separator 10 therebetween.

The negative electrode 50 including the mesh electrode current collector51 may include the mesh electrode current collector 51 and a negativeelectrode active material 55 arranged on two opposite sides of the meshelectrode current collector 51. The positive electrode 20 may include anon-porous positive electrode current collector 22 and a positiveelectrode active material 24 arranged on two opposite sides of thenon-porous positive electrode current collector 22. The negativeelectrode 30 may include a non-porous negative electrode currentcollector 32 and a negative electrode active material 34 arranged on twoopposite sides of the non-porous negative electrode current collector32.

As shown in FIG. 2 , the uppermost electrode of the electrode assembly100 may be the negative electrode 50 including the mesh electrodecurrent collector 51. The electrode assembly 100 may have a structure inwhich the negative electrode 30, the separator 10, the unit stacked bodyu1, the separator 10, and the negative electrode 50 are sequentiallystacked, the unit stacked body u1 including the positive electrode 20,the separator 10, the negative electrode 30, the separator 10, and thepositive electrode 20 that are sequentially stacked, and the negativeelectrode 50 including the mesh electrode current collector 51.

Also, though not shown in the present specification, the electrodeassembly 100 may also have a structure in which the positive electrode20, the separator 10, the unit stacked body u1, the separator 10, andthe positive electrode 40 are sequentially stacked, the unit stackedbody u1 including the negative electrode 30, the separator 10, thepositive electrode 20, the separator 10, and the negative electrode 30that are sequentially stacked, and the positive electrode 40 includingthe mesh electrode current collector.

As shown in FIG. 3 , both the uppermost electrode and the lowermostelectrode of the electrode assembly 100 may be the negative electrodes50 including the mesh electrode current collector 51. The electrodeassembly 100 may have a structure in which the negative electrode 50,the separator 10, the unit stacked body u1, the separator 10, and thenegative electrode 50 are sequentially stacked, the negative electrode50 including the mesh electrode current collector 51, and the unitstacked body u1 including the positive electrode 20, the separator 10,the negative electrode 30, the separator 10, and the positive electrode20 that are sequentially stacked.

Also, though not shown in the present specification, the electrodeassembly 100 may also have a structure in which the positive electrode40, the separator 10, the unit stacked body u1, the separator 10, andthe positive electrode 40 are sequentially stacked, the unit stackedbody u1 including the negative electrode 30, the separator 10, thepositive electrode 20, the separator 10, and the negative electrode 30that are sequentially stacked, and the positive electrode 40 includingthe mesh electrode current collector. However, it may be advantageous inaspects of manufacturing costs and stability to form the negativeelectrode 50 including the mesh electrode current collector 51 as thelowermost electrode and the uppermost electrode of the electrodeassembly 100.

As shown in FIG. 4 , the electrode assembly 100 may include the negativeelectrode 50 including the mesh electrode current collector 51 and thepositive electrode 40 including a mesh electrode current collector 41 asthe lowermost electrode and the uppermost electrode, and two unitstacked bodies u1 and u2. The electrode assembly 100 may have astructure in which the negative electrode 50, the separator 10, the unitstacked body u1, the separator 10, the negative electrode 30, a unitstacked body u2, the separator 10, and the positive electrode 40 aresequentially stacked, the negative electrode 50 including the meshelectrode current collector 51, the unit stacked body u1 including thepositive electrode 20, the separator 10, the negative electrode 30, theseparator 10, and the positive electrode 20 that are sequentiallystacked, the unit stacked body u2 including the negative electrode 30,the separator 10, the positive electrode 20, the separator 10, and thenegative electrode 30 that are sequentially stacked, and the positiveelectrode 40 including the mesh electrode current collector 41.

The positive electrode 40 including the mesh electrode current collector41 may include the mesh electrode current collector 41 and a positiveelectrode active material 45 arranged on two opposite sides of the meshelectrode current collector 41. The negative electrode 50 including themesh electrode current collector 51 may include the mesh electrodecurrent collector 51 and a negative electrode active material 55arranged on two opposite sides of the mesh electrode current collector51.

Also, though not shown in the present specification, the electrodeassembly 100 may also have a structure in which the positive electrode40, the separator 10, the unit stacked body u1, the separator 10, theunit stacked body u2, the separator 10, and the negative electrode 50are sequentially stacked, the positive electrode 40 including the meshelectrode current collector, the unit stacked body u1 including thenegative electrode 30, the separator 10, the positive electrode 20, theseparator 10, and the negative electrode 30 that are sequentiallystacked, the unit stacked body u2 including the positive electrode 20,the separator 10, the negative electrode 30, the separator 10, and thepositive electrode 20 that are sequentially stacked, and the negativeelectrode 50 including the mesh electrode current collector.

Though FIGS. 1 to 4 show the electrode assembly including only one ortwo unit stacked bodies u1 and u2, an electrode assembly including threeor more unit stacked bodies is also possible.

As described above, when the electrodes 40 and 50 including the meshelectrode current collectors 41 and 51 are provided as the lowermostelectrode and the uppermost electrode of the electrode assembly 100, notonly an irreversible capacity of a battery employing this electrodeassembly may be reduced but also a capacity increase and energy densityimprovement of the battery due to thickness reduction may be expected.

FIG. 5 is a view showing a thickness reduction effect of the negativeelectrode 50 including the mesh electrode current collector 51 comparedto the negative electrode 30 including the non-porous electrode currentcollector 32. Referring to the drawing, compared to the negativeelectrode 30 in which negative electrode active materials 34 having aconstant thickness t are arranged on two opposite sides of thenon-porous electrode current collector 32, a thickness t′ of thenegative electrode 50 including the mesh electrode current collector 51may be reduced to a level of about ½ of a thickness of the negativeelectrode 30. For example, when the negative electrode 30 is arranged onan outermost portion of the electrode assembly, the negative electrode30 including the negative electrode active materials 34 arranged on twoopposite sides of the non-porous electrode current collector 32, since areaction area in which a lithium ion reaction actually occurs is limitedto one side of the electrode current collector 32 that faces a positiveelectrode (not shown), the performance of an entire battery is notinfluenced even though a thickness of the negative electrode 50including the mesh electrode current collector 51 is reduced to a half.

Though FIG. 5 shows a thickness reduction effect of the negativeelectrode 50 including the mesh electrode current collector 51 comparedto the negative electrode 30 including the non-porous electrode currentcollector 32, the same thickness reduction effect is achieved in thecase of the positive electrode 40 including the mesh electrode currentcollector 41 compared to the positive electrode 20 including thenon-porous electrode current collector 22.

FIGS. 6 and 7 are cross-sectional views of the stacked electrodeassembly 100 according to an embodiment. Referring to the drawings, boththe lowermost electrode and the uppermost electrode of the electrodeassembly 100 may be electrodes 50′ including the mesh electrode currentcollector 51. The electrode assembly 100 may have a structure in whichthe negative electrode 50′, the separator 10, the unit stacked body u1,the separator 10, and the negative electrode 50′ are sequentiallystacked, the negative electrode 50′ including the mesh electrode currentcollector 51, and the unit stacked body u1 including the positiveelectrode 20, the separator 10, the negative electrode 30, the separator10, and the positive electrode 20 that are sequentially stacked.

Unlike the negative electrode 50 including the mesh electrode currentcollector 51 shown in FIG. 3 , the negative electrode 50′ including themesh electrode current collector 51 shown in FIGS. 6 and 7 includes anegative electrode active material 55 arranged on one side of the meshelectrode current collector 51. That is, the negative electrode 50including the mesh electrode current collector 51 shown in FIG. 3includes the negative electrode active materials 55 arranged on twoopposite sides of the mesh electrode current collector 51. In contrast,the negative electrode 50′ including the mesh electrode currentcollector 51 shown in FIGS. 6 and 7 includes the negative electrodeactive material 55 arranged on one side of the mesh electrode currentcollector 51.

More specifically, in an embodiment of FIG. 6 , the negative electrodeactive material 55 is arranged on an inner surface of the mesh electrodecurrent collector 51, or an inner surface of the mesh electrode currentcollector 51 that faces the unit stacked body u1. In an embodiment ofFIG. 7 , the negative electrode active material 55 is arranged on anouter surface of the mesh electrode current collector 51, or an outersurface opposite to the unit stacked body u1.

In embodiments of FIGS. 6 and 7 , since the negative electrode activematerial 55 is open toward two opposite sides of the mesh electrodecurrent collector 51 through openings of the mesh electrode currentcollector 51, the negative electrode active material 55 arranged on oneof an inner surface and an outer surface of the mesh electrode currentcollector 51 may act in a two-side direction of the mesh electrodecurrent collector 51. That is, the negative electrode active material 55arranged on an outer surface of the mesh electrode current collector 51and not directly facing the positive electrode 20 of the unit stackedbody u1 may also participate in an electric chemical reaction equally tothe negative electrode active material 55 arranged on an inner surface.

In the embodiment of FIG. 6 , since the negative electrode activematerial 55 arranged on the inner surface of the mesh electrode currentcollector 51 does not act through the openings of the mesh electrodecurrent collector 51 and directly faces the positive electrode of theunit stacked body u1, the embodiment of FIG. 6 may be more advantageousin increasing a battery capacity. In the embodiment of FIG. 7 , the meshelectrode current collector 51 is arranged on a relatively inner sidecompared to the negative electrode active material 55, the meshelectrode current collector 51 may avoid a direct short-circuit with acase (not shown) and thus be more advantageous in an aspect of safety.

Though not shown in the present specification, the electrode assembly100 may have a structure in which the positive electrode 40, theseparator 10, the unit stacked body u1, the separator 10, and thepositive electrode 40 are sequentially stacked, the positive electrode40 including the mesh electrode current collector, and the unit stackedbody u1 including the negative electrode 30, the separator 10, thepositive electrode 20, the separator 10, and the negative electrode 30that are sequentially stacked. In this case, the positive electrode 40including the mesh electrode current collector may include the positiveelectrode active material 45 arranged on one of an inner surface facingthe unit stacked body u1 and an outer surface opposite to the unitstacked body u1.

FIG. 8 is a cross-sectional view of a stacked electrode assemblyaccording to an embodiment. Referring to the drawings, both thelowermost electrode and the uppermost electrode of the electrodeassembly 100 may be a negative electrode 50″ including the meshelectrode current collector 51. The electrode assembly 100 may have astructure in which the negative electrode 50″, the separator 10, theunit stacked body u1, the separator 10, and the negative electrode 50″are sequentially stacked, the negative electrode 50″ including the meshelectrode current collector 51, and the unit stacked body u1 includingthe positive electrode 20, the separator 10, the negative electrode 30,the separator 10, and the positive electrode 20 that are sequentiallystacked.

Like the negative electrode 50 including the mesh electrode currentcollector 51 shown in FIG. 3 , the negative electrode 50″ including themesh electrode current collector 51 shown in FIG. 8 includes thenegative electrode active materials 55 arranged on two opposite sides ofthe mesh electrode current collector 51. However, in the embodiment ofFIG. 8 , thicknesses t1 and t2 of the negative electrode activematerials 55 respectively arranged on an inner surface and an outersurface of the mesh electrode current collector 51 are different fromeach other. For example, the thickness t1 of the negative electrodeactive materials 55 arranged on the inner surface of the mesh electrodecurrent collector 51 that faces the unit stacked body u1 may be greaterthan the thickness t2 of the negative electrode active material 55arranged on the outer surface of the mesh electrode current collector 51that is opposite to the unit stacked body u1. That is, in the embodimentof FIG. 8 , the negative electrode 50″ including the mesh electrodecurrent collector 51 may be formed in an asymmetric structure includingthe negative electrode active materials 55 respectively arranged on theinner surface and the outer surface and having the different thicknessest1 and t2.

Since the negative electrode active materials 55 are formed on twoopposite sides of the mesh electrode current collector 51, adhesiveforce between the negative electrode active materials 55 and the meshelectrode current collector 51 may be improved, and since a relativelythick negative electrode active material 55 is arranged on the innersurface of the mesh electrode current collector 51 that directly facesthe positive electrode 20 of the unit stacked body u1, a batteryperformance may be improved.

In the embodiment of FIG. 8 , in forming the negative electrode 50″including the mesh electrode current collector 51, the negativeelectrode active material 55 may be allowed to penetrate through theopenings of the mesh electrode current collector 51 and permeate to theouter surface of the mesh electrode current collector 51 by applying apredetermined pressure while coating the negative electrode activematerial 55 on one of surfaces of the mesh electrode current collector51, for example, the inner surface. Alternatively, the negativeelectrode active materials 55 having the different thicknesses t1 and t2and formed by screen printing may be press-bonded on two opposite sidesof the mesh electrode current collector 51.

Though FIG. 8 shows only the negative electrode 50″ including the meshelectrode current collector 51, the above-described technicalcharacteristics are equally applicable to the positive electrode 40including the mesh electrode current collector 41.

FIGS. 9 to 11 are cross-sectional views of negative electrodes 150, 250,and 350 each including mesh electrode current collectors 52 and 53applicable to a stacked electrode assembly according to an embodiment.

Referring to the drawings, the negative electrodes 150, 250, and 350each including the mesh electrode current collectors 52 and 53 mayinclude two or more mesh electrode current collectors 52 and 53 that areapart from each other. For example, the negative electrodes 150, 250,and 350 each including the mesh electrode current collectors 52 and 53may include two or more mesh electrode current collectors 52 and 53 thatare apart from each other in a thickness direction of the negativeelectrodes 150, 250, and 350 and are parallel to each other. Sincedifferent two mesh electrode current collectors 52 and 53 are arrangedinside one negative electrode 150 (250, 350), entire electricalconductivity of the negative electrode 150 (250, 350) may be improved,and the negative electrode active material 55 may be more stably fixed.The improvement of the electrical conductivity may lead to theimprovement of power and capacity. At least two different mesh electrodecurrent collectors 52 and 53 among different mesh electrode currentcollectors 52 and 53 arranged inside the one negative electrode 150(250, 350) may be formed to include openings at different locations orhave different aperture ratios. For example, the different meshelectrode current collectors 52 and 53 arranged inside the one negativeelectrode 150 (250, 350) may have openings at different locations orhave different aperture ratios such that electrical conductivitiessupplement or make up for each other inside the one negative electrode150 (250, 350). For example, the mesh electrode current collector 52having a relatively low aperture ratio may improve adhesive force withthe electrode active material 55. Since the mesh electrode currentcollector 53 having a relatively high aperture ratio receives theelectrode active material 55 inside a plurality of openings, aninfluence on a loading amount of the electrode active material 55corresponding to the inclusion of two or more mesh electrode currentcollectors 52 and 53 may be reduced and electrical conductivity may besupplemented. Also, in the case of the mesh electrode current collector52 having a relatively low aperture ratio, mesh is dense and thus theelectrode active material 55 does not fill the mesh properly. In thecase of the mesh electrode current collector 53 having a relatively highaperture ratio, the electrode active material 55 is not fixed properlyand may easily fall out through the opening. Therefore, characteristicsof respective mesh electrode current collectors 52 and 53 may besupplemented by combining the mesh electrode current collectors 52 and53 having different aperture ratios.

In the embodiments of FIGS. 9 and 10 , one negative electrode 150 (250)may include two different mesh electrode current collectors 52 and 53.In the embodiment of FIGS. 11 , one negative electrode 350 may includethree different mesh electrode current collectors 52 and 53. In theembodiment of FIG. 11 , two mesh electrode current collectors 52 and 53among the three mesh electrode current collectors 52 and 53 provided toone negative electrode 350 may have openings at different locations orhave different aperture ratios. For example, as shown in FIG. 11 , sincethe mesh electrode current collectors 53 having a relatively highaperture ratio are arranged on two opposite sides of the mesh electrodecurrent collector 52 having a relatively low aperture ratio, the entirenegative electrode 350 may have a symmetric structure and have asymmetric electrical conductivity in a thickness direction of thenegative electrode 350.

Though FIGS. 9 to 11 show only the negative electrode 50 including twodifferent mesh electrode current collectors 52 and 53, theabove-described technical characteristics are equally applicable to thepositive electrode 40 including two different mesh electrode currentcollectors.

FIG. 12 is a view for explaining forming of a negative electrodeincluding a mesh electrode current collector. Referring to the drawing,the mesh electrode current collector 51 may have a metal mesh shape inwhich a plurality of openings are two-dimensionally arranged. Thenegative electrode 50 may be formed by press-bonding two layers of thenegative electrode active materials 55 on two opposite surfaces of themesh electrode current collector 51 in a direction in which the twolayers of the negative electrode active materials 55 face each other,the two layers of the negative electrode active materials 55 beingformed by screen printing. Here, the mesh electrode current collector 51may include a plurality of metal wires extending in two differentdirections, the metal wires being weaved. That is, the mesh electrodecurrent collector 51 has a generally flat plate-shaped structure but isnot formed in a completely flat shape and may have a shape weaved in afabric form. The mesh electrode current collector 51 formed in thismanner may have a plurality of curves in two opposite surface directionsand increase adhesive force with the electrode active materials 55arranged on two opposite surfaces of the mesh electrode currentcollector 51.

For another method of forming the negative electrode 50 including themesh electrode current collector 51, there may be a method of immersingthe mesh electrode current collector 51 in a bathtub (not shown)containing slurry for forming the negative electrode active materials55, and collectively forming the negative electrode active materials 55on two opposite surfaces of the mesh electrode current collector 51.

Also, a coating method may be applied, the coating method includingcoating the negative electrode active material 55 on one side of themesh electrode current collector 51 so as to form the negative electrode50 in which the negative electrode active material 55 is formed on oneside of the mesh electrode current collector 51.

Though FIG. 12 shows only the forming of the negative electrode 50including the mesh electrode current collector 51, the above-describedtechnical characteristics are equally applicable to the positiveelectrode 40 including the mesh electrode current collector 41.

FIGS. 13A to 13D are photos of various shapes of mesh electrode currentcollectors.

The mesh electrode current collector according to an embodiment may havea shape weaved in a metal mesh structure as in FIG. 13A, or have a shapeweaved in a fabric form as in FIG. 13B. Also, the mesh electrode currentcollector according to an embodiment may have a shape in which aplurality of openings are punched in a single thin-plate sheet as inFIG. 13C. Also, the mesh electrode current collector according to anembodiment may have openings of irregular shapes as in FIG. 13D. Forexample, the mesh electrode current collector having openings ofirregular shapes may be prepared in a non-woven fabric shape.

The mesh electrode current collector according to an embodiment mayinclude various shapes of regular openings as shown in FIGS. 13A to 13C,or include openings of irregular shapes as shown in FIG. 13D.

The mesh electrode current collectors 41 and 51 may have a shape inwhich a plurality of openings are two-dimensionally arranged in a basematerial having a sheet shape on the whole. For example, the meshelectrode current collectors 41 and 51 may have a metal mesh shape.

For example, the mesh electrode current collectors 41 and 51 may includeat least one of Al, Ti, V, CR, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Ag, W,Pt, SUS, and a combination thereof.

In the case where an electrode including the mesh electrode currentcollector 51 is the negative electrode 50, the mesh electrode currentcollector 51 may include a Cu metal mesh. In the case where an electrodeincluding the mesh electrode current collector 41 is the positiveelectrode 40, the mesh electrode current collector 41 may include an Almetal mesh. For example, in the case where an electrode including themesh electrode current collector 51 is the negative electrode 50, themesh electrode current collector 51 may be a Cu metal mesh. In the casewhere an electrode including the mesh electrode current collector 41 isthe positive electrode 40, the mesh electrode current collector 41 maybe an Al metal mesh.

For example, a thickness of the mesh electrode current collectors 41 and51 may be about 10 μm to about 500 μm. Specifically, for example, athickness of the mesh electrode current collectors 41 and 51 may beabout 50 μm to about 500 μm. Specifically, for example, a thickness ofthe mesh electrode current collectors 41 and 51 may be about 50 μm toabout 200 μm. When the electrodes 40 and 50 including the mesh electrodecurrent collectors 41 and 51 having the above thickness range areemployed in a lowermost portion and/or an uppermost portion of abattery, an irreversible capacity of the battery may be reduced.

The mesh electrode current collectors 41 and 51 may include an openingin an appropriate range so as to reduce an irreversible capacity andimplement a desired capacity of the battery.

FIG. 14 is a photo of a mesh electrode current collector having adifferent number of openings or different aperture ratios. A size of anopening, the number of openings, and an aperture ratio in each of meshelectrode current collectors shown in FIGS. 14A to 14F are provided inTable 1.

TABLE 1 Size of opening Number of openings Aperture ratio (inch) (ppi)(%) (a) 1/32 20 52 (b) 1/50 30 41 (c) 1/64 40 36 (d) 0.009 60 31 (e)0.007 80 31 (f) 0.005 100 30

In Table 1, a size (inch) of an opening denotes a diameter of theopening, and the number of openings denotes the number of openings perinch (ppi, pore per inch). In FIG. 14 , it is shown that the number ofopenings per inch (ppi) gradually increases and an aperture ratiodecreases from (a) on the left to (f) on the right.

An increase in the number of openings per inch (ppi) in the meshelectrode current collector means that openings having a small size aredensely arranged. This means that an aperture ratio is reduced as muchas that.

The number of openings or an aperture ratio of the mesh electrodecurrent collectors 41 and 51 may be designed in different ranges for theelectrodes 40 and 50 in which an electrode active material is arrangedon one side of the relevant mesh electrode current collectors 41 and 51,and the electrodes 40 and 50 in which electrode active materials arearranged on two opposite sides of the relevant mesh electrode currentcollectors 41 and 51.

The electrode including the electrode active materials on two oppositesides of the mesh electrode current collectors 41 and 51 may maintainadhesive force with the electrode active material even though theelectrode includes the mesh electrode current collectors 41 and 51having a relatively high aperture ratio (a relatively small number ofopenings). Also, within a limit in which the electrode active materialis properly fixed, when the mesh electrode current collectors 41 and 51have a high aperture ratio (a relatively small number of openings), aloading amount of the electrode active material that may penetrate intothe openings may be increased, and the electrode active materials formedon two opposite surfaces of the mesh electrode current collectors 41 and51 may be closely connected to each other through the openings of themesh electrode current collectors 41 and 51 that are sufficientlyformed, and thus may facilitate an electrical chemical reaction. Morespecifically, as in the embodiments of FIGS. 3 and 4 , when theelectrodes 40 and 50 including the mesh electrode current collectors 41and 51 include the electrode active materials 45 and 55 arranged on twoopposite sides of the mesh electrode current collectors 41 and 51, thenumber of openings (ppi) of the mesh electrode current collectors 41 and51 may be 30 or less per inch, or an aperture ratio of the meshelectrode current collectors 41 and 51 may be 40% or more.

In the case of the electrodes 40 and 50 including the electrode activematerial on one side of the mesh electrode current collectors 41 and 51,when the electrodes 40 and 50 include the mesh electrode currentcollectors 41 and 51 having a relatively small aperture ratio (arelatively large number of openings), the electrodes 40 and 50 areadvantageous in maintaining excellent adhesive force with the electrodeactive material. More specifically, as in the embodiments of FIGS. 6 and7 , when the electrode (ex. the negative electrode 50′) including themesh electrode current collector 51 includes the electrode activematerial (ex. a negative active material 55) arranged on one side of themesh electrode current collectors 41 and 51, the number of openings(ppi) of the mesh electrode current collector 51 may be 30 or more perinch, or an aperture ratio of the mesh electrode current collector 51may be 40% or less.

In other words, since the mesh electrode current collectors 41 and 51 inwhich the number of openings (ppi) is 30 or more per inch, or anaperture ratio is 40% or less (the mesh electrode current collectorhaving a small aperture ratio) may maintain excellent adhesive forcewith the electrode active material, both the electrodes 40 and 50 may beprovided, the electrodes 40 and 50 including the electrode activematerials arranged on two opposite sides or one side of the meshelectrode current collectors 41 and 51. In contrast, in the case of themesh electrode current collectors 41 and 51 in which the number ofopenings (ppi) is 30 or less per inch, or an aperture ratio is 40% ormore (the mesh electrode current collector having a high apertureratio), it may be advantageous to provide the electrodes 40 and 50 inwhich the electrode active materials are arranged on two oppositesurfaces of the mesh electrode current collectors 41 and 51 inmaintaining excellent adhesive force with the electrode active material.When an electrode in which the electrode active material is arranged onone side of the mesh electrode current collectors 41 and 51 is provided,the mesh electrode current collectors 41 and 51 having a relatively highaperture ratio, adhesive force with the electrode active material may bereduced.

As shown in FIGS. 9 to 11 , since the electrode (ex. the negativeelectrodes 150, 250, and 350) including two or more different meshelectrode current collectors 52 and 53 may properly fix the electrodeactive material by using the two different mesh electrode currentcollectors 52 and 53, even the mesh electrode current collectors 52 and53 including a relatively small number of openings or having arelatively high aperture ratio (the mesh electrode current collectorhaving a high aperture ratio) may constitute the electrode in which theelectrode active material is arranged on one side.

FIG. 15 is a view of an electrode 5 including an electrode currentcollector 2 and an electrode active material 4 according to acomparative example, the electrode current collector 2 including athree-dimensional pore having a metal foam shape, and the electrodeactive material 4 penetrating into the pore of the electrode currentcollector 2. In the electrode 5 having this shape, since an entirethickness of the electrode 5 is limited by the electrode currentcollector 2 having a metal foam shape, the electrode 5 has a relativelythick thickness compared to the electrodes 40 and 50 including the meshelectrode current collectors 41 and 51 according to an embodiment. Also,a loading amount of the electrode active material 4 is limited by avolume corresponding to a fine pore of the electrode current collector 2having a metal foam shape. Since a volume is increased due to theelectrode current collector 2 having a relatively thick metal foam shapebut a loading amount of the electrode active material 4 is limited bythe volume of the fine pore, energy density per same volume is limitedand the energy density is relatively reduced.

Hereinafter, a method of manufacturing the lithium battery is described.

The positive electrode 40 including the mesh electrode current collector41 may be manufactured as below.

First, the mesh electrode current collector 41 is prepared. Next, apositive electrode active material composite may be manufactured bymixing a positive electrode active material as an electrode activematerial, a binder, and a selectively conductive material in solvent.The positive electrode 40 including the mesh electrode current collector41 may be manufactured by forming the above-manufactured positiveelectrode active material composite in a layered structure throughscreen printing and bonding the positive electrode active materialcomposite on two opposite surfaces of the mesh electrode currentcollector through pressing, or immersing the mesh electrode currentcollector in a bathtub containing the positive electrode active materialcomposite, or coating the positive electrode active material composite,and then drying the mesh electrode current collector.

For positive electrode active material used for the positive electrodeactive material composite, all of materials generally used in the artmay be used. For example, a compound expressed in one of chemicalformulas may be used, the chemical formulas includingLi_(a)A_(1-b)B_(b)D₂(where, 0.90≤a≤1, and 0≤b≤0.5);Li_(a)E_(1-b)B_(b)O_(2-c)D_(c)(where, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05);LiE_(2-b)B_(b)O_(4-c)D_(c)(where, 0≤b≤0.5, 0≤c≤0.05);Li_(a)Ni_(1-b-c)Co_(b)B_(c)D_(α)(where, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05,0≤α≤2); Li_(a)Ni_(1-b-c)Co_(b)B_(c)O_(2-α)F_(α)(where, 0.90≤a≤1,0≤b≤0.5, 0≤c≤0.05, 0≤α≤2); Li_(a)Ni_(1-b-c)Co_(b)B_(c)O_(2-α)F₂(where,0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0≤α≤2);Li_(a)Ni_(1-b-c)Mn_(b)B_(c)D_(α)(where, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05,0≤α≤2); Li_(a)Ni_(1-b-c)Mn_(b)B_(c)O_(2-α)F_(α)(where, 0.90≤a≤1,0≤b≤0.5, 0≤c≤0.05, 0≤α≤2); Li_(a)Ni_(1-b-c)Mn_(b)B_(c)O_(2-α)F₂(where,0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0≤α≤2); Li_(a)Ni_(b)E_(c)G_(d)O₂(where,0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1);Li_(a)Ni_(b)Co_(c)Mn_(d)G_(e)O₂(where. 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5,0≤d≤0.5, 0.001≤e≤0.1); Li_(a)NiG_(b)O₂(where, 0.90≤a≤1, 0.001≤b≤0.1);Li_(a)CoG_(b)O₂(where, 0.90≤a≤1, 0.001≤b≤0.1); Li_(a)MnG_(b)O₂(where,0.90≤a≤1, 0.001≤b≤0.1); Li_(a)Mn₂G_(b)O₄(where, 0.90≤a≤1, 0.001≤b≤0.1);QO₂; QS₂; LiQS₂; V₂O₅; LiV₂O₅; LiIO₂; LiNiVO₄;Li_((3-f))J₂(PO₄)₃(0≤f≤2); Li_((3-f))Fe₂(PO₄)₃(0≤f≤2); LiFePO₄.

In the above chemical formulas, A is Ni, Co, Mn, or a combinationthereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare-earth element,or a combination thereof; D is O, F, S, P, or a combination thereof; Eis Co, Mn, or a combination thereof; F is F, S, P, or a combinationthereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combinationthereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc,Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or acombination thereof.

For example, LiCoO₂, LiMn_(x)O_(2x) (x=1, 2), LiNi_(1-x)Mn_(x)O_(2x)(0<x<1), LiNi_(1-x-y)Co_(x)Mn_(y)O₂ (0≤x≤0.5, 0≤y≤0.5), FePO₄.

A binder used for the positive electrode active material composite is acomponent assisting coupling of the positive electrode active materialand a conductive material and coupling of the positive electrode activematerial and a current collector. The binder is added as much as 1 to 50weight portion based on 100 weight portion of the positive electrodeactive material. For example, the binder may be added in the range of 1to 30 weight portion, 1 to 20 weight portion, or 1 to 15 weight portionbased on 100 weight portion of the positive electrode active material.The binder may be one of polyvinylidene fluoride (PVdF), polyvinylidenechloride, polybenzimidazole, polyimide, polyvinyl acetate,polyacrylonitrile, polyvinyl alcohol, carboxymethyl cellulose (CMC),starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene,polystyrene, poly(methyl methacrylate, polyaniline,acrylonitrile-butadiene-styrene, a phenolic resin, an epoxy resin,polyethylene terephthalate, polytetrafluoroethylene, polyphenylensulfide, polyamide imide, polyether imide, polyethylene sulfone,polyamide, polyacetal, polyphehyleneoxide, polybutylene terephthalate,ethylene propylene diene monomer (EPDM), sulfonated EPDM,styrene-butadiene rubber (SBR), fluoro rubber, and a combinationthereof.

For the conductive material, any material that is generally used for alithium battery may be used. Examples of the conductive material includea conductive material including: a carbon-based material includingcarbon black, acetylene black, ketjenblack, a carbon fiber; ametal-based material including metal powder or metal fiber including Cu,Ni, Al, and Ag; and a conductive polymer including polyphenylenederivatives or a mixture thereof. Content of a conductive material maybe appropriately adjusted and used. For example, a weight ratio of thepositive electrode active material and the conductive material may be inthe range of 99:1 to 90:10.

For the solvent, N-methyl-pyrrolidone (NMP), acetone, water, etc. may beused. For the content of the solvent, 1 to 40 weight portion may be usedbased on 100 weight portion of the positive electrode active material.When the content of the solvent is in the above range, an operation offorming the active material is easy.

In the case of the negative electrode 50 including the mesh electrodecurrent collector 51, the negative electrode 50 may be manufactured bythe same method as a method of manufacturing the positive electrode 40including the mesh electrode current collector 41 except that a negativeelectrode active material is used as an electrode active material. Also,the same binder, the same conductive material, and the same solvent asthose of the positive electrode may be used for the negative electrodeactive material composite.

For the negative electrode active material, all of materials that aregenerally used in the art may be used. For example, the negativeelectrode active material may include at least one of a lithium metal, ametal that may be alloyed with lithium, a transition metal oxide, anon-transition metal oxide, and a carbon material.

For example, the metal that may be alloyed with lithium may include Si,Sn, Al, Ge, Pb, Bi, Sb, an Si—Y alloy (where Y is an alkali metal, analkaline earth metal, a Group 13 element, a Group 14 element, atransition metal, a rare-earth element or a combined element thereof, Sinot being included), an Sn—Y alloy (where Y is an alkali metal, analkaline earth metal, a Group 13 element, a Group 14 element, atransition metal, a rare-earth element or a combined element thereof, Snnot being included), etc. The element Y may include Mg, Ca, Sr, Ba, Ra,Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb,Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti,Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.

For example, the transition metal oxide may include a lithium titaniumoxide, a vanadium oxide, and a lithium vanadium oxide.

For example, the non-transition metal oxide may include SnO₂,SiO_(x)(0<x<2).

The carbon material may include crystalline carbon, amorphous carbon ora mixture thereof. Examples of the crystalline carbon may includegraphite such as natural graphite having an irregular shape, a plateshape, a flake shape, a spherical shape, or a fiber shape, or artificialgraphite. Examples of the amorphous carbon may include soft carbon orhard carbon, mesophase pitch carbide, and calcinationed cork.

Next, the positive electrode 20 may be manufactured by a method offorming the above-manufactured positive electrode active materialcomposite in a predetermined shape or coating the positive electrodeactive material composite on the non-porous positive electrode currentcollector 22, thereby forming the positive electrode active material 24on at least one side of the current collector. Also, the negativeelectrode 30 may be manufactured by a method of forming theabove-manufactured negative electrode active material composite in apredetermined shape or coating the negative electrode active material onthe non-porous negative electrode current collector 32, thereby formingthe negative electrode active material 34 on at least one side of thecurrent collector.

The non-porous positive electrode and negative electrode currentcollectors 22 and 32 are not particularly limited as long as they havehigh conductivity while not causing a chemical change to a relevantbattery independently. For example, the non-porous positive electrodeand negative electrode current collectors 22 and 32 may include at leastone of Al, Cu, Ni, Ti, and stainless steel. A base material may includea material formed by performing surface-processing on a surface of Al,Cu, Ni, stainless steel through electric plating or ion-deposition byusing coating components such as Ni, Cu, Al, Ti, Au, Ag, Pt, and Pd, ora material formed by coating the surface of the main material throughmethods such as dip or pressing by using nano particles of these coatingcomponents. Also, the current collector may include the above-describedconductive material covering the base including a non-conductivematerial. The current collector may include a fine uneven structure on asurface thereof. The uneven structure may increase adhesive force withan active material to be coated on a base material. The currentcollector may generally have a thickness from about 10 μm to about 30μm.

Next, according to the above-described embodiment, a stacked electrodeassembly may be manufactured by sequentially stacking a lowermostelectrode, a separator, one or more unit stacked bodies, a separator,and an uppermost electrode.

In this case, a positive electrode active material used for each ofpositive electrodes may be the same or different from each other. Also,a negative electrode active material used for each of negativeelectrodes may be the same or different from each other.

For the separators, all of separators that are generally used for alithium battery may be used. Particularly, a separator having a lowresistance against ion transfer of electrolyte and having an excellentelectrolyte-containing ability is suitable. For example, the separatormay include a material including a glass fiber, polyester, Teflon,polyethylene, polypropylene, polytetrafluoroethylene, and a combinationthereof. The separator may be a non-woven fabric or a woven form. Anopening of the separator may have a diameter of about 0.01 μm to about10 μm. A thickness of the separator may be about 5 μm to about 300 μm.In the above range, capacity reduction of a battery per unit volume maybe minimized and safety against inner short-circuit may be secured. Forexample, a thickness of the separator may be about 8 μm to about 30 μm.

After that, a lithium battery may be manufactured by inserting thestacked electrode assembly in a case having a shape such as a squareshape and a cylindrical shape, and then injecting electrolyte.

In this case, the electrolyte may include non-water-based electrolyteand lithium salt. For the non-water-based electrolyte, non-waterelectrolyte, organic solid electrolyte, etc. may be used.

The non-water electrolyte may include, for example, a deprotonatedorganic solvent including N-methyl-pyrrolidone, propylene carbonate(PC), ethylene carbonate (EC), butylenes carbonate, dimethyl Carbonate(DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC),gamma-butyrolactone (GBL), 1,2-dimethoxyethane) (DME), tetrahydrofuran(THF), 2-methyl tetrahydrofuran, dimethylsulfoxide (DMSO),1,3-dioxolane, formamide, dimethylformamide, acetonitrile, nitromethane,methyl formate, methyl acetate, phosphate trimester, tri methoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane,1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, ether,methyl propionate, propionic acid, and ethyl propionate.

Examples of the organic solid electrolyte may include, for example,polyethylene derivatives, polyethylene oxide derivatives, polypropyleneoxide derivatives, phosphorus ester polymer, polylysine, polyestersulfide, polyvinyl alcohol, polyvinylidene fluoride, or a polymerincluding an ionic dissociation group.

For the lithium salt, all of materials that are generally used for alithium battery may be used. For a material that may be well dissolvedin the non-water-based electrolyte, at least one of, for example, LiCl,LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂, LiAsF₆,LiSbF₆, LiAlCl₄, CH₃SO₃Li, C₄F₉SO₃Li, (CF₃SO₂)₂NLi, lithium chloroborate, lower aliphatic carbonic acid lithium, 4 phenyl boric acidlithium, or imide may be used.

Also, an SEI layer is formed on a surface of a negative electrode in theelectrolyte. To maintain the SEI layer, the electrolyte may includevinylene carbonate (VC), and catechol carbonate (CC). Selectively, toprevent overcharge, the electrolyte may include a redox-shuttle typeadditive including n-butyl ferrocene, and benzene replaced with halogen.Selectively, the electrolyte may include an additive for forming a filmincluding cyclohexylbenzene and biphenyl. Selectively, to improve aconduction characteristic, the electrolyte may include a cation receptorsuch as crown ether-based compound, and anion receptor such asboron-based compound. Selectively, the electrolyte may additionallyinclude, as an incombustible material, phosphate-based compound such astrimethyl phosphate, tris (2,2,2-trifluoroethyl) phosphate (TFP), andhexamethoxy cyclotriphosphazene (HMTP).

When needed, to further improve safety of a lithium battery by assistingthe forming of a stable SEI layer or a film on a surface of anelectrode, the electrolyte may further include an additive includingtris (trimethylsilyl) phosphate (TMSPa), lithium difluorooxalateborate(LiFOB), propanesultone (PS), succinonitrile (SN), LiBF₄, for example,silane compound having a functional group that may form a siloxanecoupling such as acryl, amino, epoxy, methoxy, vinyl, and silazanecompound such as hexamethyldisilazane. Specifically, the electrolyte mayfurther include, for example, propanesultone (PS), succinonitrile (SN),and LiBF₄.

For example, the electrolyte may be manufactured by adding a lithiumsalt such as LiPF₆, LiClO₄, LiBF₄, and LiN(SO₂CF₃)₂ to a mixed solventof a circular carbonate of EC or PC, which is a high dielectric solvent,and a linear carbonate of DEC, DMC, or EMC which is a low-viscositysolvent.

Since the lithium battery has an excellent life characteristic and anexcellent high efficiency characteristic, the lithium battery may beused for an electric vehicle (EV). For example, the lithium battery maybe used for hybrid vehicles such as plug-in hybrid electric vehicles(PHEV). The lithium battery may be also used for electric bicycles,electrically-drive tools, and other all purposes requiring high power, ahigh voltage, and high temperature driving.

The lithium battery may include a lithium secondary battery.

Example embodiments are described in more detail through an embodimentand a comparative example below. However, since the embodiment isprovided to describe a technical spirit as an example, the scope of thepresent disclosure is not limited thereto.

Embodiment 1

(Manufacturing of a Negative Electrode Including a Mesh ElectrodeCurrent Collector)

A Cu metal mesh is prepared as a mesh electrode current collector. Also,a negative electrode active material composite is manufactured by mixingnegative electrode active material graphite 98 weight % (manufactured byShanghai Shanshan Co.) and a binder SBR 2 weight % (manufactured by ZeonCo.) in solvent of N-methyl pyrrolidone. The negative electrode ismanufactured by coating the manufactured negative electrode activematerial composite on two opposite surfaces of the Cu metal mesh anddrying the same.

(Manufacturing of a Positive Electrode)

A positive electrode active material composite is manufactured by mixinga positive electrode active material LiCoO₂ 97.5 weight % (manufacturedby Umicore Co.), a conductive material carbon black 1 weight % (productname ECP, manufactured by Lion Co.), and a binder PVdF 1.5 weight %(product name Solef, manufactured by Sovay Co.) in solvent of N-methylpyrrolidone. The positive electrode having a thickness of about 120 μmis manufactured by coating the above-manufactured active materialcomposite on two opposite surfaces of an aluminum foil current collectorhaving a thickness of 15 μm, drying and pressing the same.

(Manufacturing of a Negative Electrode)

A negative electrode active material composite is manufactured by mixingnegative electrode active material graphite 98 weight % (manufactured byShanghai Shanshan Co.) and a binder SBR 2 weight % (manufactured by ZeonCo.) in solvent of N-methyl pyrrolidone. The negative electrode having athickness of about 145 μM is manufactured by coating theabove-manufactured active material composite on two opposite surfaces ofa Cu foil current collector having a thickness of about 10 μm, dryingand pressing the same.

(Manufacturing of an Electrode Assembly)

A separator including a polyethylene (PE) film (manufactured by TorayCo.) is prepared, and as shown in FIG. 3 , the electrode assembly ismanufactured by sequentially stacking the negative electrode includingthe above-manufactured mesh electrode current collector, a separator,the manufactured positive electrode, a separator, the manufacturednegative electrode, a separator, the manufactured positive electrode, aseparator, and the negative electrode including the manufactured meshelectrode current collector.

(Manufacturing of a Lithium Secondary Battery)

A pouch-type lithium secondary battery is manufactured by inserting theelectrode assembly in a pouch-type case, and then injecting electrolyteincluding lithium salt of 1.3 M LiPF₆ to solvent in which ethylenecarbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate(DMC) are mixed at a volume ratio of 1:1:1.

Embodiment 2

(Manufacturing of a Negative Electrode Including Two Different MeshElectrode Current Collectors)

A Cu metal mesh is prepared as a mesh electrode current collector. Inthis case, for the mesh electrode current collector, two different meshelectrode current collectors are prepared, the two different meshelectrode current collectors having openings at different locations orhaving different aperture ratios. As shown in FIG. 9 , a mesh electrodecurrent collector 52 having a relatively low aperture ratio in which thenumber of openings per inch (ppi) is 100, and a mesh electrode currentcollector 53 having a relatively high aperture ratio in which the numberof openings per inch (ppi) is 40 are prepared.

Also, a negative electrode active material composite is manufactured bymixing negative electrode active material graphite 98 weight %(manufactured by Shanghai Shanshan Co.) and a binder SBR 2 weight %(manufactured by Zeon Co.) in solvent of N-methyl pyrrolidone. Thenegative electrode is manufactured by coating the manufactured negativeelectrode active material composite on the Cu metal mesh and drying thesame. In this case, referring to FIG. 9 , a negative electrode activematerial composite is primarily coated on the mesh electrode currentcollector 52 having a relatively low aperture ratio in which the numberof openings per inch (ppi) is 100, and then the mesh electrode currentcollector 53 having a relatively high aperture ratio in which the numberof openings per inch (ppi) is 40 is arranged thereon, and next, thenegative electrode active material composite is secondarily coated. Thepositive electrode and the negative electrode are manufactured by thesame method as that of Embodiment 1.

(Manufacturing of the Electrode Assembly)

A separator including polyethylene (PE) film (manufactured by Toray Co.)is prepared, and as shown in FIG. 3 , the electrode assembly ismanufactured by sequentially stacking the negative electrode includingthe manufactured mesh electrode current collector, a separator, themanufactured positive electrode, a separator, the manufactured negativeelectrode, a separator, the manufactured positive electrode, aseparator, and the negative electrode including the manufactured meshelectrode current collector.

(Manufacturing of a Lithium Secondary Battery)

A pouch-type lithium secondary battery is manufactured by inserting theelectrode assembly in a pouch-type case, and then injecting electrolyteincluding lithium salt of 1.3 M LiPF₆ to solvent in which ethylenecarbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate(DMC) are mixed at a volume ratio of 1:1:1.

COMPARATIVE EXAMPLE

A lithium battery is manufactured by the same method as that ofEmbodiment 1 except that a negative electrode is manufactured by using aCu foil current collector instead of the negative electrode includingthe mesh electrode current collector.

An appraisal example: a capacity and energy density of a lithium batteryare measured.

To determine whether an irreversible capacity is reduced, the lithiumsecondary batteries manufactured in Embodiments 1 and 2, and Comparativeexample were charged to a charging cut-off voltage of 4.3 V with acurrent of 0.2 C rate at 25° C. during a constant current mode (CCmode), and charged until a current becomes 0.05 C rate with a voltage of4.3 V maintained during a constant voltage mode (CV mode). Subsequently,the lithium secondary batteries were discharged to a discharging cut-offvoltage of 3.0 V during a constant current mode of 0.2 C. After that,capacities and energy densities of lithium secondary batteriesmanufactured in Embodiments 1 and 2 and Comparative example weremeasured and represented in Table 2 below.

Here, the energy density may be represented as below.

${{Energy}{density}} = \frac{{battery}{capacity}({mAh}) \times {battery}{voltage}(V)}{{battery}{volume}(L)}$

TABLE 2 An electrode The number of including a Energy unit stacked meshelectrode Capacity density bodies current collector (mAh) (Wh/L)Embodiment 1 1 Lowermost 79 360 electrode and uppermost electrodeEmbodiment 2 1 Lowermost 79 343 electrode and uppermost electrodeComparative 1 Non 75 300 example

As shown in Table 2, it is found that Embodiments 1 and 2 in which thelowermost electrode and the uppermost electrode include the meshelectrode current collector, have excellent capacity and energy densitycompared to Comparative example in which there is no electrode includingthe mesh electrode current collector.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to a battery as an energy sourcethat is chargeable and dischargeable, and various apparatuses that usethe battery as a driving power source.

The invention claimed is:
 1. A stacked electrode assembly, comprising; afirst electrode at a first portion of the stacked electrode assembly,the first electrode being a negative electrode and including a negativeelectrode active material, wherein the first electrode includes a firstmesh electrode current collector, and a second mesh electrode currentcollector, and a third mesh electrode current collector in the thicknessdirection of the first electrode, the first mesh electrode currentcollector is interposed between the second mesh electrode currentcollector and the third mesh electrode current collector, and the secondand third mesh electrode current collectors have openings at differentlocations or have different aperture ratios from the first meshelectrode current collector; a second electrode at a second portion ofthe stacked electrode assembly; a unit stacked body between the firstelectrode and the second electrode; a first separator between the firstelectrode and the unit stacked body; and a second separator between theunit stacked body and the second electrode, wherein: the unit stackedbody includes a first positive electrode, a first negative electrode,and a third separator, the third separator being between the firstpositive electrode and the first negative electrode, and the first meshelectrode current collector is spaced apart from the second meshelectrode current collector in a thickness direction of the firstelectrode.
 2. The stacked electrode assembly of claim 1, wherein thesecond electrode further includes a third mesh electrode currentcollector and a fourth mesh electrode current collector, the third meshelectrode current collector being spaced apart from the fourth meshelectrode current collector in a thickness direction of the secondelectrode.
 3. The stacked electrode assembly of claim 1, wherein thefirst electrode includes the negative electrode active material locatedon one side of the first mesh electrode current collector.
 4. Thestacked electrode assembly of claim 1, wherein the first electrodeincludes the negative electrode active material located on two oppositesides of the second mesh electrode current collector.
 5. The stackedelectrode assembly of claim 1, wherein the first electrode has anasymmetric shape in which a thickness of the negative electrode activematerial located on one side thereof is different from a thickness ofthe negative electrode active material located on another side thereof.6. The stacked electrode assembly of claim 1, wherein the firstelectrode includes the negative electrode active material located insidean opening of each of the first mesh electrode current collector and thesecond mesh electrode current collector.
 7. The stacked electrodeassembly of claim 1, wherein the first mesh electrode current collectorhas openings at different locations from openings in the second meshelectrode current collector.
 8. The stacked electrode assembly of claim1, wherein the first mesh electrode current collector has a differentaperture ratio from an aperture ratio of the second mesh electrodecurrent collector.
 9. The stacked electrode assembly of claim 1,wherein, in the unit stacked body, the first positive electrode and thefirst negative electrode each include a non-porous electrode currentcollector and an electrode active material arranged on at least one sideof the non-porous electrode current collector.
 10. The stacked electrodeassembly of claim 1, wherein the unit stacked body has a bi-cellstructure stacked in a sequence of one of: the first negative electrode,the third separator, the first positive electrode, a fourth separator,and a second negative electrode, or the first positive electrode, thethird separator, the first negative electrode, a fourth separator, and asecond positive electrode.
 11. The stacked electrode assembly of claim1, wherein the first mesh electrode current collector and the secondmesh electrode current collector each have a metal mesh shape in which aplurality of openings are arranged two-dimensionally.
 12. The stackedelectrode assembly of claim 1, wherein the first mesh electrode currentcollector and the second mesh electrode current collector each includeat least one of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Ag, W,Pt, stainless steel, or a combination thereof.
 13. The stacked electrodeassembly of claim 1, wherein the first mesh electrode current collectorand the second mesh electrode current collector each have a thickness of10 μm to 500 μm.
 14. The stacked electrode assembly of claim 3, whereina number of openings (ppi) of the first mesh electrode current collectoris 30 or more per inch, or an aperture ratio of the first mesh electrodecurrent collector is 40% or less.
 15. The stacked electrode assembly ofclaim 4, wherein a number of openings (ppi) of the second mesh electrodecurrent collector is 30 or less per inch, or an aperture ratio of thesecond mesh electrode current collector is 40% or more.
 16. A lithiumbattery comprising: the stacked electrode assembly according to claim 1.17. A stacked electrode assembly, comprising; a first electrode at afirst portion of the stacked electrode assembly; a second electrode at asecond portion of the stacked electrode assembly; a unit stacked bodybetween the first electrode and the second electrode; a first separatorbetween the first electrode and the unit stacked body; and a secondseparator between the unit stacked body and the second electrode,wherein: the unit stacked body includes a first positive electrode, afirst negative electrode, and a third separator, the third separatorbeing between the first positive electrode and the first negativeelectrode, the first electrode includes a first mesh electrode currentcollector and a second mesh electrode current collector, the first meshelectrode current collector being spaced apart from the second meshelectrode current collector in a thickness direction of the firstelectrode, the first electrode includes a third mesh electrode currentcollector, which is spaced apart from each of the first mesh electrodecurrent collector and the second mesh electrode current collector in thethickness direction of the first electrode, the first mesh electrodecurrent collector is interposed between the second mesh electrodecurrent collector and the third mesh electrode current collector, andthe second and third mesh electrode current collectors have openings atdifferent locations or have different aperture ratios from the firstmesh electrode current collector.